export {}
type Readonly<T> = {
 readonly [P in keyof T]: T[P];
};
interface IPerson{
    name: string;
    age: number;
}
type person = Readonly<IPerson>
let p:person = {
    name: "John",
    age:10
}
// 无法分配到 "age" ，因为它是只读属性。
// p.age = 12;
